WinNonlin for Win95/WinNT
(32-bit)
(Nonlinear Least Squares Analysis of Sedimentation
Equilibrium Data)
-
Sedimentation Equilibrium Equation:
Data is fitted by the WinNonlin program to the following
equation,
,
where dc is the concentration
offset of the first data point (this is generally 0 for absorption data
and some arbitrary value for interference data), q(i) is the degree of
association for the ith associated species, Ci(r) is the concentration
of the ith species at radius r, K1,i is the equilibrium constant
for the association of monomer to the q(i)-mer, C1(r) is the
concentration of the monomer at radius r, n is the total number of species
present in the model being used for fitting the data, and can be between
1 (no association) and 5 for the current version of WinNonlin.
The variable C1(r) may be expanded
to
,
where C1,0 is the monomer concentration
at the first point of the data set (the natural logarithm of this is used
by the program as LnA), x, x0 are
the value of r2/2 and r2/2 at the first point of
the data set (used as a reference position), B is the colligative second
virial coefficient with the assumption of gi
= (g1)q(i), and s
is the reduced molecular weight as defined by
,
where M1 is the monomer molecular weight,
is the partial specific volume, r is the solvent
density and w is the rotor speed in radians
per sec. The variables that can be fitted
by WinNonlin are dc (as deltaY), C1,0
(as LnA), q(i) (as Ni ), K1,i (as LnKi), s
and B.
This version of Nonlin has been adapted for
PCs running Win95 or WinNT (Workstation) from the OpenVMS version.
There is a maximum of 15 data sets and/or a total of 8000 data points.
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